Soldering flux



Patented Feb. 1936 UNITED I STATES.

PATENT OFFICE signor to The Grasselll Chemi Company,

Cleveland, Ohio, a corporation of Delaware No Drawing. Application October 31, 1983,

Serial No. 696,118 I 9 Claims. (Cl- 148-28) This invention is directed to a flux and the process of using it in the soft soldering of metals, such as tin plate, galvanized iron. copper, brass, etc.

I have found that phosphates which decompose at or below the temperatures used in soft soldering constitute excellent fluxes. The temperatures encountered in commercial soft soldering will usually range between about 400 F. and about 650 F. Whatever the temperature 10 range employed a suitable phosphate flux may be selected, it being only ny that the phosphate selected decompose at or below the temperature at which the soldering takes place. It is not necessary that the phosphates decompose for below soldering temperatures. It is only necessary that the thermal decomposition take place prior to, or during the soldering operation at the V temperatures requiredior the solderinl; ration.

Among the organic and inorganic thermally de-' 2 cornposable phosphates which I have found suitable I'may mention, for example, diammonium phosphate, disodium phosphate, amine phosphates, giyceryl phosphates, butyl phosphates, etc.

I may alsouse mixed phosphate salts, such as microcomic salt, which are thermally decomposable at or below soldering temperatures.

The soldering operation takes place, of course,

in the presence ofthe decomposition products of the phosphate selected. There may also be pres so cut some undecomposed phosphates and some partially decomposed phosphates. As the operation continues the decomposition proceeds until,

usually, the-phosphates are entirely decomposed. Microcosmic salt, for example, on heating decomposes to form sodiummetaphosphate. I may, accordingly. use sodium metaphosphate and similar decomposition products as fluxes, although I prefer to use, as heretofore stated, the thermally decomposable phosphates.

'dlynewfluxesmaybeusedintheusualmanners,"in dry form, as a paste, or in solution.

For example, I may make a saturated solution" of diammonium phosphate in water and apply it in one of the usual ways to the metal to be soldered. After applyin the flux the soldering operation proceeds as usual.

I claim: I

1. Ida process of'soft soldering the step of applying a flux comprising a maior amount of a phosphate thermally decomposable at or below soft soldering temperatures. 1o

'2. In a process of soft soldering the step of applying solder in the presence of the decomposithermally decomposable at or below soft solder- 25 ing temperatures. v

6. Ina process of soft soldering the step comprising applying a flux consisting of a phosphate thermally decomposableat or below soft soldering temperatures.

7.-In a'process of soft soldering the step comprising applyin a flux consisting substantially of a phosphate thermally decomposable at or be low soft soldering temperatures.

8. ma process of soft soldering the'step oom- 35 prising applying a flux consisting substantially or diammonium phosphate.

9. In a process of soft soldering the step comprising applying a flux consisting substantially of a microcosmic salt. 40

K. SCHWEITZER. 

